Definition of water : a chemical substance, with chemical formula H2O, that is clear, colorless, oderless, and tasteless liquid that may also occur in various forms such as gas (water vapour) and solid (ice). Water is regarded as the universal solvent primarily due to its chemical and physical properties. It is one of the substances essential to life. Biomolecules (DNA, proteins, polysaccharides, etc.) are dissolved in water. It is also one of the requirements for photosynthesis.
Physical Properties of Water:
In liquid water, the molecules of hydrogen and oxygen are close together but are able to slip past one another, which is why it flows. Examples of this are a river, a waterfall, or water coming out of your faucet.
When the temperature drops, the water molecules slow down and become sluggish. As it becomes cold enough for the water to freeze, the molecules rearrange themselves into hollow rings.
This is why water expands when it freezes, unlike most other substances which contract. This expansion in the solid phase is the reason why ice cubes float in a glass of water. The ice is actually lighter or less dense than the liquid water.
Water also occurs in the gaseous phase, such as steam rising from a boiling tea kettle. As water is heated, the molecules move about violently, colliding with one another, until some break free and form a vapor, or gas.
The heat capacity of water enables the oceans to act as huge reservoirs of solar warmth and keeps our weather from going to great extremes of heat or cold. The moderating effect of water is noticeably absent from a desert, where days tend to be very hot and nights cold.
The degree to which water has a distinctive taste or odor depends on the types of substances dissolved in it. Since water is not changed chemically when it acts as a solvent, it can be recovered for reuse after undesirable dissolved substances are removed. The amount of dissolved substances in water is affected by factors such as water temperature and the nature of the material water moves through.
Conductivity is the ability of a substance to carry an electric current. Water will conduct an electric current only if dissolved ions are present because water molecules do not act as a conductor. Measuring conductivity is a good way to determine the amount of dissolved solids in a sample of water and, thus, to determine its purity.
Chemical properties of water:
Water – a polar molecule – tends to be slightly positive on the hydrogen side and slight negative on the oxygen side. The electrostatic bond between the positive hydrogen side of this molecule and other negative ions or polar molecules is called a hydrogen bond.
Molecules and ions with which water forms hydrogen bonds (such as sodium chloride) are hydrophylic. On the other hand, Ions and molecules that do not form hydrogen bonds with water are hydrophobic.
Kept relatively close together, the moluecules at room temperature are unable to dissipate sufficiently to form a gas. Temperatures of 212°F (or 100°C) are required to break the hydrogen bonds and convert liquid water into water vapor.
Once ionic compounds dissolve, their anions and cations circulate through the water allowing further reactions to occur. Thus, water also sponsors and facilitates chemical reactions.
Water also retains heat, so its temperature falls slowly. This means that larger systems of water (such as the ocean or a body) tend to maintain more or less constant temperatures, which in turn helps the earth (and us) to maintain relatively constant temperatures.
Floating ice is critical to life on Earth. Bodies of water freeze from the top down, providing an insulating layer of ice that keeps the water below from freezing. For the organisms living below the surface, this property helps them to survive the cold weather.
The structure of water molecule:
A water molecule consists of two hydrogen atoms and one oxygen atom. The three atoms make an angle; the H-O-H angle is approximately 104.5 degrees. The center of each hydrogen atom is approximately 0.0957 nm from the center of the oxygen atom.
Because oxygen is more electronegative than hydrogen (in other words, electrons tend to be in the neighborhood of the oxygen), the hydrogen atoms end up with a partial positive charge and the oxygen atom with a partial negative charge. This separation of charge produces a net dipole moment on the molecule; for the isolated water molecule this dipole moment is approximately 1.85 Debye units.
This molecular structure leads to hydrogen bonding, which is a stabilized structure in which a hydrogen atom is in a line between the oxygen atom on its own molecule and the oxygen on another molecule. These hydrogen bonds, with their extra attractive energy, are the cause of many of the unusual properties of water, including its large heat of vaporization and its expansion upon freezing.
Hydrogen Bonding in Water: Strong intermolecular forces called hydrogen bonds are formed between water molecules. Hydrogen bonding is responsible for many of the unusual characteristics of water, namely its relatively high boiling point (and low vapor pressure) for a molecule of its size, the wide range of temperature that this small molecule exists in liquid form, its lower density in the solid form compared with its liquid form, and its propensity to form dome-like droplets on surfaces.
Hydrogen bonds are formed between electronegative atoms of one molecule and hydrogens that are bound to electronegative atoms of another molecule. They have roughly 5% the strength of a covalent bond. For water, the hydrogen bonds form between the oxygen of one water molecule and a hydrogen atom of another water molecule. The typical distance for a hydrogen bond is approximately 2 angstroms.
Ice forms a regular hexagonal packing structure. In ice, the structure is rigid and molecules are held in place by a vast network of hydrogen bonds. Because of the open nature of the hexagonal lattice, ice is less dense than water.
In water’s liquid form, water molecules form extensive hydrogen bonds, on average 2-3 per molecule. Notice that there is not a regular structure to water. It is also important to understand that each hydrogen bond is transient. The large heat of vaporization of water is largely due to the need to break all of the hydrogen bonds in order to produce water vapor.
Theoretical water clusters
It has been postulated that water in its liquid form does form some regular longer-lived structures termed clusters.
Water and oil don’t mix Water’s strong intermolecular hydrogen bonds cause the molecules to associate strongly with each other, and exclude hydrophobic compounds such as oil and lipids to such a degree that the hydrophobic compounds are pushed together. This is what causes oil droplets and oil slicks to form in water. It is also responsible for the formation of lipid micelles, as well as the lipid membranes that make the exterior of cells and cellular organelles.
Water vapor In water vapor, the water molecules are very separated from each other. Thus, the water molecules rarely interact at a close enough distance to form hydrogen bonds. However, water vapor’s behavior is far from that of an ideal gas, in large part because of the strength of intermolecular interactions when two molecules do pass near each other.
Zamzam water: Zamzam is the name of the well that provides the water to billions of people, have thirstily drunk from throughout history, especially during the Hajj pilgrimage.
some of the features of Zamzam water:
Zamzam water: the power drink
One of the miracles of Zamzam water is its ability to satisfy both thirst and hunger. One of the Companions of the Prophet said that before Islam, the water was called “Shabbaa’ah” or satisfying. It was filling and helped them nourish their families.
After Islam, this powerful ability to quench thirst and fill stomachs remained. Prophet Muhammad said: “The best water on the face of the earth is the water of Zamzam; it is a kind of food and a healing from sickness.”
According to the Muslim collection of Hadith, Abu Dharr al-Ghifari, a Companion (Sahabi), noted that when he first arrived in Makkah during the early days of Islam, not only did he satisfy his hunger and thirst but he survived only on Zamzam water for a whole month.
More recently, in the last few decades, scientists have collected samples of Zamzam water and they have found certain peculiarities that make the water healthier, like a higher level of calcium.
Zamzam water: a cure for sickness Apart from its ability to serve as satisfying food and drink, Zamzam water’s health benefits are also commended. Prophet Muhammad (peace and blessings be upon him and his family) said it was a healing
from sickness. This is why pilgrims to Makkah to this day collect it in bottles to bring for relatives and friends back home who are ill.
Prophet Muhammad (peace and blessings be upon him and his family) used to carry Zamzam water in pitchers and water skins back to Madinah. He used to sprinkle it over the sick and make them drink it. Wahab Ibn Munabbah, who was from the second generation of Muslims, said ‘I swear by Him in whose possession my life is, Allah Ta’ala will relieve the person of all illnesses who drinks Zamzam to his fill and will also grant him good health.’
Water presents everywhere
Water is everywhere: Water covers 70.9% of the Earth’s surface, and is vital for all known forms of life. On Earth, 96.5% of the planet’s water is found mostly in oceans; 1.7% in groundwater; 1.7% in glaciers and the ice caps of Antarctica and Greenland; a small fraction in other large water bodies, and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Only 2.5% of the Earth’s water is freshwater, and 98.8% of that water is in ice and groundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth’s freshwater (0.003%) is contained within biological bodies and manufactured products.
Liquid water is found in bodies of water, such as an ocean, sea, lake, river, stream, canal, pond, or puddle. The majority of water on Earth is sea water. Water is also present in the atmosphere in solid, liquid, and vapor states. It also exists as groundwater in aquifers.
The water in our body: Water is The Major component of the Human Body On average, the body of an adult human being contains 60% water. Most of the water in the human body is contained inside our cells. In fact, our billions of cells must have water to live.
The total amount of water in our body is found in three main locations: within our cells (two-thirds of the water), in the space between our cells and in our blood (one-third of the water). For example, a 70-kg man is made up of about 42L of total water.
28 litres is intracellular water
14L is found in extracellular fluid of which
– 3L is blood plasma,
– 1L is the transcellular fluid (cerebrospinal fluid, ocular, pleural, peritoneal and synovial fluids)
– 10L is the interstitial fluid (including lymph), which is an aqueous medium surrounding cells. Actually, the amount of water a body contains varies according to certain contexts: The body of a newborn is composed of more water (75%) than that of an elderly person (50%). Also, the more muscular a body is, the more water it contains. Conversely, the more fat in the body, the less water the body contains – as body fat has little water.
Also, all our vital organs contain different amounts of water: the brain, the lungs, the heart, the liver and the kidneys contain a large quantity of water – between 65 to 85% depending on the organ (2), while bones contain less water (but still 31%!). For all those reasons, water is life.
The Functions of Water Water is involved in many of our body’s vital functions
Water removes waste products including toxins that the organs’ cells reject, and removes them through urines and faeces.
Water participates in the biochemical break-down of what we with Water inside our cell: The study of the live cell is fraught difficulty, as most procedures change it from its native state. The key to understanding the cell comes from acknowledging the one constituent that has often been ignored: water. The significance of water for the cell
becomes clear when we seek to solve big puzzles, such as ‘How are potassium ions able to maintain a high concentration inside cells whereas sodium ions are found mainly outside?’ and ‘How do cells remain functional even when large holes are made in their surface membranesndoTv
There are at least four views as to how the water inside the cell affects its function: • The water mostly acts as an uncomplicated environment for the cellular processes, which are determined by the structure of the macromolecules only. Although this view seems the one most promoted in current textbooks by default, it is rapidly losing favour due to its inability to explain natural processes. • The water forms polarised multi-layers over extended protein surfaces, as proposed for many years by Gilbert Ling . There is much experimental support for the foundations of this theory but little experimental support for the required structural changes in the proteins or the involvement of extended protein surfaces, as proposed. • The water is involved in intracellular changes between ‘sol’ and ‘gel’ states as more recently promoted by Gerald Pollack . This is an interesting and useful idea but without a clear molecular mechanism. • The water actively changes the density of its hydrogen bonded structuring to enable diverse intracellular processes, in a manner compatible with the basic ideas of both Gilbert Ling and Gerald Pollack.
Ocean: An ocean (from Greek ‘S2Keavòs, “okeanos” Oceanus) is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth’s surface (~3.6×108 km2) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.
More than half of this area is about 4,267 metres
(13,999 ft) deep. Average oceanic salinity is around 35
parts per thousand (%o) (3.5%), and nearly all seawater has salinity in the range of 30 to 38 %o. Scientists estimate that 230,000 marine species are currently known, but the total could be up to 10 times that number.
The ocean also is a life medium for many many organisms Different color and species can’t live without water.
A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean.It is also used sometimes to describe a large saline lake that lacks a natural outlet, such as the Caspian Sea
Water stagnation: Water stagnation occurs when water stops flowing. Stagnant water can be a major environmental hazard. It’s a life medium of many bacteria and parasites.
The north and south poles: The water is a major of the north and south poles on our earth, and it presents as an ice and water there ,There are a huge mountains of ices which is a cold water ,and as we know the water is necessary for the organisms witch live there.
The Discovery of Water Ice on Mercury: Mercury would seem to be one of the least likely places in the solar system to find ice. The closest planet to the Sun has temperatures which can reach over 700 K. The local day on the surface of Mercury is 176 earth-days, so the surface is slowly rotating under a relentless assault from the Sun. Nonetheless, Earth-based radar imaging of Mercury has revealed areas of high radar reflectivity near the north and south poles, which could be indicative of the presence of ice in these regions (1-3). There appear to be dozens of these areas with generally circular shapes. Presumably, the ice is located within permanently shadowed craters near the poles, where it may be cold enough for ice to exist over long periods of time. The discovery of ice on the Earth’s moon can only serve to strengthen the arguments for ice on Mercury.
Ice on the moon: The ice originally appeared to be mixed in with the lunar regolith (surface rocks, soil, and dust) at low concentrations conservatively estimated at 0.3 to 1 percent. Subsequent data from Lunar Prospector taken over a longer period has indicated the possible presence of discrete, confined, near-pure water ice deposits buried beneath as much as 18 inches (40 centimeters) of dry regolith, with the water signature being stronger at the Moon’s north pole than at the south (4). The ice was thought to be spread over 10,000 to 50,000 square km (3,600 to 18,000 square miles) of area near the north pole and 5,000 to 20,000 square km (1,800 to 7,200 square miles) around the south pole, but the latest results show the water may be more concentrated in localized areas (roughly 1850 square km, or 650 square miles, at each pole) rather than being spread out over these large regions. The estimated total mass of ice is 6 trillion kg (6.6 billion tons). Uncertainties in the models mean this estimate could be off considerably.
Water is life !